Make sure the entire group is together, and break the seal (use it). Everyone in the group should get a quest advance.

Next, the quest will require you to go inside the Mage Academy at 40.3S 49.6W and kill 6 Revenant Rhetors. (see map) You will fight some solo Gurog and Revenants on the way down the stairs and into the first room. Kill them, go down the stairs, cross the room and go upstairs. At the top, you will come to a path that branches left and right. Go right and follow it down and to your left (there will be a few left turns as you go down). You will come to an open room with 2 Revenant Praetors. Kill them and move forward to the Revenant Rhetor zone.

Be careful here because it's easy to pull entire groups at once. Facing north, go forward and past the first crossing. You'll eventually see the portal to Rytheran's Sanctum, but you can't enter until you kill the Rhetors. Keep going north and into the door on your left. Open the door carefully and kill the 3 Rhetors inside. There is also a Gurog Warlock group monster guarding the Singularity Trove here. Kill or mezz it and finish the Rhetors part of the quest.

With all the Rhetors killed, go back east to the Sanctum portal you passed earlier. Enter the portal.

When you enter Rytheran's Sanctum, move north, cross the room with the tables and don't turn. Kill the Revenants here and go up the stairs. The next room will have 3 Revenant Magisters. Kill them, then take the south path to Rytheran's room.

Inside, you will see 2 Revenants guarding the boss, Garaena. Everyone that has a Weapon of the Sun's Blaze should use it to apply the effect: Cripple Rytheran. This prevents the powerful attack Spectral Doom that can easily kill any player in their 40s in a single stroke. Kill the boss, and the quest will be completed. Everyone will receive their XP reward.